Kidney stones and other naturally occurring stones in the urinary bladder, gall bladder, kidneys, or ureter can be exquisitely painful, and in the past have required surgical relief. Excision or destruction of stones in the bladder can often be accomplished by entrance thereto through the urethra with an endoscope for viewing, and either a retracting or fracturing tool, or a lithotripter for generating a hydraulic shockwave in the immediate vicinity of the stone or stones. Obviously, a lithotripter must be small to enter through the urethra, or through a small surgical incision into the kidney, the bladder, or the gall bladder. A shockwave is generated by a high voltage spark jumping between two closely spaced electrodes. However there has heretofore been no way of concentrating the energy directly on the stone and the energy (with the exception of that hitting the stone) generally radiates in all directions from the electrodes. This radiated energy is unwanted and can possibly perforate the surrounding tissue which can lead to many complications of an otherwise simple procedure.